The present invention relates to an ink jet system printer provided with means for compensating for any charge distortion in ink drops.
It is well known in the art of ink jet system printer that high speed printing performances require increase in frequency of ink drop formation. Furthermore, it is required to increase ink pressure but such requirement is not fully satisfied in view of size and weight of the printers. An alternate approach to increase the ink drop formation frequency is to decrease ink drop spacing. In accordance with such approach, the charging of a specific ink drop is influenced by an electric field established due to the preceding ink drops to thereby occur charge distortion and, therefore, the specific ink drop being currently charged can assume the amplitude of charge smaller than a desired one. This causes faulty printing. In the past, several approaches were suggested in order to reduce such charge distortion, as disclosed U.S. Pat. No. 3,631,511 entitled "DROP CHARGE COMPENSATED INK DROP VIDEO PRINTER" on Dec. 28, 1971 wherein the charge on an ink drop being formed is compensated upon the charge on the drop already formed, and U.S. Pat. No. 3,562,757 entitled "GUARD DROP TECHNIQUE FOR INK JET SYSTEMS" on Feb. 9, 1971 wherein guard drops are provided between the charged drops which act as a shield to minimize the adverse affects of drop charge repulsion.
However, the inventor's experiments show that in the former arrangement distortion of around 10% develops when .lambda. d.apprxeq. 4.8 wherein d is the diameter of a charging electrode and .lambda. is the ink drop spacing, while in the latter arrangement printing speed is decreased by one-half, accompanying distortion of around 8%.
It is, therefore, an object of the present invention to provide an improved ink jet system printer having a charge compensator.